This disclosure relates to color image output systems. Specifically, this disclosure relates to a system and method of controlling an image output device to produce a consistent spectrum of colors and color separations.
To meet customer demands, image output devices such as a printer or display need to produce a consistent spectrum of colors over time. For example, customers want a printing system to produce a particular colored document consistently from day to day, or print job to print job.
To control the color rendering consistency of a printing device, the printing device is typically characterized and calibrated prior to being shipped to a customer. The characterization and calibration process produces a set of LUTs (look-up tables) which correlate a standardized set of target colors with the appropriate device dependent color space values necessary to produce the target colors with the printing device. For example, a Pantone® color spectrum may be utilized as a color target reference and the LUTs produced by the characterization and calibration process are device dependent CMYK color space representations of the Pantone® target colors. This characterization and calibration process is generally referred to as profiling a device or printer.
To accomplish the profiling of a printing device, a spectrophotometer or other image sensing device is used to measure the colorimetric properties of the produced images. These measured colorimetric properties provide an objective basis of comparison to the reference target color set and provide the necessary feedback to iteratively generate accurate device dependent LUTs. Stated another way, device independent CMYK values are correlated to the reference target color set, and the LUT correlates the reference target color set device independent CMYK values to the device dependent CMYK values.
Notably, the profiling methods discussed above can be applied to xerographic and direct marking color printing system, such as an ink jet printer.
To properly profile or calibrate a color printer, a printer model is first generated which maps a plurality of colorant combinations to a device independent color space, such as LAB, etc. To create an ICC profile, the inverse of the printer model can be used to map from a device independent color space to device dependent color space, for example, CMYK.
To create device independent color space representations of printed colors, patterns or series of patches are printed and, subsequently, a spectraphotometer measures the spectral properties of the printed patterns. The spectral properties associated with the printed patterns are used to generate a model for the printer.